Modern poultry operations process chicken, turkey, duck or other poultry birds through an automated system of slaughter, evisceration, cleaning and packaging. Due to its very nature, the process of evisceration exposes the exterior body surfaces and inner body cavities of the birds to the contents of the digestive tract. In so doing, the bird is exposed to potentially pathogenic microorganisms.
Several methods have been developed, with some regulated into use, to reduce the overall contamination rate of processed poultry. Among these are co-current and counter-current chill tank systems and the addition of various processing aids to these tanks. Current regulations require that each processed bird pass through a chilled water system to reduce its carcass temperature from ambient to 35.degree. F. Several systems are employed to accomplish this.
Generally accepted methodologies utilize mechanical paddles or spirals to submerge and move the bird through the chilling bath. Regulations do not stipulate whether the water flow be co-current, that is in the direction the birds are being moved, or counter-current, where the birds move against the flow. The regulation does require, however, that a makeup and overflow system be provided in the chill system sufficient enough to provide a replacement of the water at a rate not less than one gallon per bird per minute.
While these methods provide adequate cleaning of the carcass and reduce the body temperature to prolong the product's freshness, they are not particularly effective at reducing enteric pathogens. To correct this, several modifications to the chill tank operation have been proposed and evaluated. The most promising of these has been the addition of chlorine to the water supplying the chill tank. Chlorine addition rates have been evaluated from rather low levels to levels as high as 5 parts per million of free chlorine in the tank's effluent flows. While some efficacy using this method has been reported, concern exists due to the potential for the formation of chlorinated organic compounds and their subsequent effect upon ingestion.
Several methods, including competitive bacterial exclusion and the treatment of processed birds with peroxides, acids, surfactants and other compounds have been proposed. See, for example, U.S. Pat. Nos. 3,104,170; 4,683,618; and 4,770,884. Some of these methods are being evaluated and some have been eliminated due to their inherent negative effects on the birds or concern for the safety of the resulting product when ingested.
U.S. Pat. No. 4,849,237 discloses a method for sanitizing poultry carcasses in a poultry processing plant. The method involves, after scalding, defeathering, eviscerating and chilling the bird being treated, sanitizing the bird with ozonated water. The application of the ozonated water to the bird involves both immersing the external portion of the bird in a bath of ozonated water and, while immersed in the bath, subjecting the bird to jets of ozonated water directed into the body cavity of the carcass and along the outside of the carcass. This method is problematical in that it requires an additional area outside of the processing plant production line to synthesize the ozone gas and dissolve it in water prior to treatment. This is to prevent ozone from being released into the atmosphere of the work place and creating a health hazard to the employees. As a result, the costs of treating the birds are significantly increased.
Pressure to find an effective method to reduce the likelihood of food related illnesses has been increasing with continued pressure being seen from both the public and the media. Commonly assigned U.S. Pat. No. 5,069,922 teaches a process for treating poultry carcasses to control salmonellae growth. More specifically, this method comprises treating the poultry with a treatment solution having a pH above about 11.5 and containing a trialkali metal orthophosphate.
To utilize this process on a commercial scale, a long tank is fabricated to allow the plant's overhead monorails to pull the birds through a bath containing the treatment solution. While this method is very successful, it requires large volumes of the trialkali metal orthophosphate to be used and requires a large physical area in a poultry treating plant to accommodate the tank for practical operation.
Accordingly, there exists a need in the art for a method for treating poultry (or other edible animals) to significantly reduce the amounts of potentially pathogenic bacteria of the enteric groups while providing a method which is commercially viable on a plant scale.